1. Field of the Invention
This invention relates to digital in-circuit testers. More particularly, this invention relates to a user-interactive test system for generating testing waveforms and measuring the outputs of devices to which those testing waveforms are inputted. The use of the term "in-circuit" means that the device or circuit under test does not have to be isolated or removed from the surrounding circuits in order to apply test signals and to monitor the output of the device.
2. Descriotion of the Related Art
U.S. Pat. No. 4,216,539, incorporated herein by reference, and assigned to the assignee of the present application, discloses an in-circuit digital tester. That patent discloses a digital test signal generator with each pin in a "bed of nails" fixture capable of generating a wide variety of digital test signals to test components in a circuit under test. U.S. Pat. No. 4,339,819, incorporated herein by reference, and assigned to the assignee of the present application, discloses a programmable sequence generator for in-circuit digital testing. That patent discloses a circuit for generating data bus and control input test signals to test bus-oriented electrical components, such as microprocessors, in a circuit under test.
Some companies have produced in-circuit testers which can display on a CRT waveforms outputted by a device-under-test (DUT). The Genrad 2270 series manufactured by Genrad in Concord, Mass., is such a device. However, apparently that device cannot record or edit the output waveforms of the DUT. Some companies have produced logic analyzer workstations for debugging microprocessors. These workstations utilize personal computers. One such workstation is produced by Northwest Instrument Systems, Inc., Beaverton, Ore.
The workstations currently produced suffer from various deficiencies. Existing workstations cannot provide stimuli in the middle of a circuit board. Stated another way, these workstations cannot "in-circuit back drive". These workstations are also unable to edit recorded DUT outputted waveforms and then use the edited waveforms as input stimuli for the same DUT in a subsequent test. Furthermore, even for those workstations which utilize personal computers, none of those workstations have a user-friendly interface, such as a computer "mouse", for user interface with the personal computer.
Thus, there exists a need for a workstation that allows easy and efficient user interface with the personal computer, and has a capability of not only viewing measured waveforms, but also recording and editing those measured waveforms, and then using those edited waveforms as stimuli for retesting the DUT.